The present invention relates to a process control system, and more particularly, to a method of predictive maintenance of a process control system having fluid movement in a pipeline and, further, having instrumentation devices for measuring parameters (or process variables) of the fluid.
In present systems, pressure, or differential pressure, of a fluid is measured as it moves (flows) through a pipeline. Further, in present day systems, a large amount of effort is used to eliminate the "flow noise" of the fluid as it flows through a pipeline (or more simply pipe). Fluid noise is inherent in almost any fluid as it flows through a pipeline. The noise is generally a random, low frequency noise and has always been a prime consideration in the designs of the pressure devices, flow meter devices, . . . and like devices. Specifically, flow noise is an undesirable component of fluid flow in a pipeline and is sought to be eliminated. If a noise signal which results from the fluid noise is permitted to propagate through the devices attempting to measure parameters of the fluid flowing in the pipeline, then, for example, a device measuring pressure will measure pressure plus all the deviations of pressure of the fluid caused by the noise signal component. It is highly undesirable to measure a process variable which fluctuates based on the noise which is being detected in the pipeline. Thus, efforts are made to eliminate the noise component of a signal outputted from the measuring device utilizing well-known techniques. The result is a quiet, stable measurement of the pressure (as an example).
The present invention utilizes the noise signal, which has previously been separated and discarded, and analyzes the noise signal to extract data from the noise. Inherent in the noise is information about the flow, such as a popped bearing failure, a leak in the pipe, a pump cavitation, . . . . The present invention thereby provides an improvement over current and past systems by providing a method of predictive maintenance of a process system having fluids flowing in a pipeline and utilizing devices for measuring process variables (or parameters) of the control system.